The overall objectives of the project are the elucidation of molecular events occurring during mammalian oogenesis, fertilization, and early pre and postimplantation development. Our goals for the current year are: A. The in vitro translation of messengers RNA'a obtained from oocytes and very early embryos will be attempted. B. Protein synthesis during various stages of oocyte growth and maturation will be analyzed by two-dimensional electrophoresis. C. The split-embryo technique will be used for the study of developmental mutations which affect early embryonic development. D. Studies on the comparative protein synthesis of teratocarcinoma cells and of normal early postimplantation embryos will be carried out with two-dimensional electrophoresis to define better the similarities and differences between normal embryonic cells and teratocarcinoma stem cells.